Source code for psychopy.web
#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""Library for working with internet connections"""
# Part of the PsychoPy library
# Copyright (C) 2002-2018 Jonathan Peirce (C) 2019-2024 Open Science Tools Ltd.
# Distributed under the terms of the GNU General Public License (GPL).
import pathlib
import sys
import socket
import re
from psychopy import logging
from psychopy import prefs
import urllib.request
import urllib.error
import urllib.parse
# default 20s from prefs, min 2s
TIMEOUT = max(prefs.connections['timeout'], 2.0)
socket.setdefaulttimeout(TIMEOUT)
# global proxies
proxies = None # if this is populated then it has been set up already
class NoInternetAccessError(Exception):
"""An internet connection is required but not available
"""
# global haveInternet
haveInternet = None # gets set True or False when you check
[docs]def haveInternetAccess(forceCheck=False):
"""Detect active internet connection or fail quickly.
If forceCheck is False, will rely on a cached value if possible.
"""
global haveInternet
if forceCheck or haveInternet is None:
# try to connect to a high-availability site
sites = ["http://www.google.com/", "http://www.opendns.com/"]
for wait in [0.3, 0.7]: # try to be quick first
for site in sites:
try:
urllib.request.urlopen(site, timeout=wait)
haveInternet = True # cache
return True # one success is good enough
except Exception: # urllib.error.URLError:
# socket.timeout() can also happen
pass
else:
haveInternet = False
return haveInternet
[docs]def requireInternetAccess(forceCheck=False):
"""Checks for access to the internet, raise error if no access.
"""
if not haveInternetAccess(forceCheck=forceCheck):
msg = 'Internet access required but not detected.'
logging.error(msg)
raise NoInternetAccessError(msg)
return True
def tryProxy(handler, URL=None):
"""
Test whether we can connect to a URL with the current proxy settings.
`handler` can be typically `web.proxies`, if `web.setupProxy()` has been
run.
:Returns:
- True (success)
- a `urllib.error.URLError` (which can be interrogated with `.reason`)
- a `urllib.error.HTTPError` (which can be interrogated with `.code`)
"""
if URL is None:
URL = 'http://www.google.com' # hopefully google isn't down!
req = urllib.request.Request(URL)
opener = urllib.request.build_opener(handler)
try:
opener.open(req, timeout=2).read(5) # open and read a few characters
return True
except urllib.error.HTTPError as err:
return err
except urllib.error.URLError as err:
return err
def getPacFiles():
"""Return a list of possible auto proxy .pac files being used,
based on the system registry (win32) or system preferences (OSX).
"""
pacFiles = []
if sys.platform == 'win32':
try:
import _winreg as winreg # used from python 2.0-2.6
except ImportError:
import winreg # used from python 2.7 onwards
net = winreg.OpenKey(
winreg.HKEY_CURRENT_USER,
"Software\\Microsoft\\Windows\\CurrentVersion\\Internet Settings")
nSubs, nVals, lastMod = winreg.QueryInfoKey(net)
subkeys = {}
for i in range(nVals):
thisName, thisVal, thisType = winreg.EnumValue(net, i)
subkeys[thisName] = thisVal
if ('AutoConfigURL' in list(subkeys.keys()) and
len(subkeys['AutoConfigURL']) > 0):
pacFiles.append(subkeys['AutoConfigURL'])
elif sys.platform == 'darwin':
import plistlib
prefs_loc = pathlib.Path('/Library/Preferences/SystemConfiguration/preferences.plist')
if prefs_loc.exists():
with open(prefs_loc, 'rb') as fp :
sysPrefs = plistlib.loads(fp.read())
networks = sysPrefs['NetworkServices']
# loop through each possible network (e.g. Ethernet, Airport...)
for network in list(networks.items()):
netKey, network = network # the first part is a long identifier
if 'ProxyAutoConfigURLString' in network['Proxies']:
pacFiles.append(network['Proxies']['ProxyAutoConfigURLString'])
return list(set(pacFiles)) # remove redundant ones
def getWpadFiles():
"""Return possible pac file locations from the standard set of .wpad
locations
NB this method only uses the DNS method to search, not DHCP queries, and
so may not find all possible .pac locations.
See http://en.wikipedia.org/wiki/Web_Proxy_Autodiscovery_Protocol
"""
# pacURLs.append("http://webproxy."+domain+"/wpad.dat")
# for me finds a file that starts: function FindProxyForURL(url,host)
# dynamcially chooses a proxy based on the requested url and host; how to
# parse?
domainParts = socket.gethostname().split('.')
pacURLs = []
for ii in range(len(domainParts)):
domain = '.'.join(domainParts[ii:])
pacURLs.append("http://wpad." + domain + "/wpad.dat")
return list(set(pacURLs)) # remove redundant ones
def proxyFromPacFiles(pacURLs=None, URL=None, log=True):
"""Attempts to locate and setup a valid proxy server from pac file URLs
:Parameters:
- pacURLs : list
List of locations (URLs) to look for a pac file. This might
come from :func:`~psychopy.web.getPacFiles` or
:func:`~psychopy.web.getWpadFiles`.
- URL : string
The URL to use when testing the potential proxies within the files
:Returns:
- A urllib.request.ProxyHandler if successful (and this will have
been added as an opener to the urllib)
- False if no proxy was found in the files that allowed successful
connection
"""
if pacURLs == None: # if given none try to find some
pacURLs = getPacFiles()
if pacURLs == []: # if still empty search for wpad files
pacURLs = getWpadFiles()
# for each file search for valid urls and test them as proxies
for thisPacURL in pacURLs:
if log:
msg = 'proxyFromPacFiles is searching file:\n %s'
logging.debug(msg % thisPacURL)
try:
response = urllib.request.urlopen(thisPacURL, timeout=2)
except urllib.error.URLError:
if log:
logging.debug("Failed to find PAC URL '%s' " % thisPacURL)
continue
pacStr = response.read().decode('utf-8')
# find the candidate PROXY strings (valid URLS), numeric and
# non-numeric:
pattern = r"PROXY\s([^\s;,:]+:[0-9]{1,5})[^0-9]"
possProxies = re.findall(pattern, pacStr + '\n')
for thisPoss in possProxies:
proxUrl = 'http://' + thisPoss
handler = urllib.request.ProxyHandler({'http': proxUrl})
if tryProxy(handler) == True:
if log:
logging.debug('successfully loaded: %s' % proxUrl)
opener = urllib.request.build_opener(handler)
urllib.request.install_opener(opener)
return handler
return False
[docs]def setupProxy(log=True):
"""Set up the urllib proxy if possible.
The function will use the following methods in order to try and
determine proxies:
#. standard urllib.request.urlopen (which will use any
statically-defined http-proxy settings)
#. previous stored proxy address (in prefs)
#. proxy.pac files if these have been added to system settings
#. auto-detect proxy settings (WPAD technology)
.. note:
This can take time, as each failed attempt to set up a proxy
involves trying to load a URL and timing out. Best
to do in a separate thread.
Returns
_________
True (success) or False (failure)
"""
global proxies
# try doing nothing
proxies = urllib.request.ProxyHandler(urllib.request.getproxies())
if tryProxy(proxies) is True:
if log:
logging.debug("Using standard urllib (static proxy or "
"no proxy required)")
# this will now be used globally for ALL urllib opening
urllib.request.install_opener(urllib.request.build_opener(proxies))
return 1
# try doing what we did last time
if len(prefs.connections['proxy']) > 0:
proxConnPref = {'http': prefs.connections['proxy']}
proxies = urllib.request.ProxyHandler(proxConnPref)
if tryProxy(proxies) is True:
if log:
msg = 'Using %s (from prefs)'
logging.debug(msg % prefs.connections['proxy'])
# this will now be used globally for ALL urllib opening
opener = urllib.request.build_opener(proxies)
urllib.request.install_opener(opener)
return 1
else:
if log:
logging.debug("Found a previous proxy but it didn't work")
# try finding/using a proxy.pac file
pacURLs = getPacFiles()
if log:
logging.debug("Found proxy PAC files: %s" % pacURLs)
proxies = proxyFromPacFiles(pacURLs) # installs opener, if successful
if (proxies and
hasattr(proxies, 'proxies') and
len(proxies.proxies['http']) > 0):
# save that proxy for future
prefs.connections['proxy'] = proxies.proxies['http']
prefs.saveUserPrefs()
if log:
msg = 'Using %s (from proxy PAC file)'
logging.debug(msg % prefs.connections['proxy'])
return 1
# try finding/using 'auto-detect proxy'
pacURLs = getWpadFiles()
proxies = proxyFromPacFiles(pacURLs) # installs opener, if successful
if (proxies and
hasattr(proxies, 'proxies') and
len(proxies.proxies['http']) > 0):
# save that proxy for future
prefs.connections['proxy'] = proxies.proxies['http']
prefs.saveUserPrefs()
if log:
msg = 'Using %s (from proxy auto-detect)'
logging.debug(msg % prefs.connections['proxy'])
return 1
proxies = 0
return 0
